Shares of UnitedHealth Group are surging before the market open Friday as Warren Buffett’s Berkshire Hathaway disclosed that it recently purchased shares of the beleaguered insurer.

Warren Buffett's Berkshire Hathaway increased its holdings in UnitedHealth Group stock, and also added positions in D.R. Horton, Lamar Advertising, and Nucor.

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UnitedHealth Group ( UNH 12.04%) has been a solid dividend growth stock for years. Generally, its yield has been fairly low, due to the stock's rising value. Even as the healthcare insurance giant has grown its dividend, its yield hasn't been particularly high or noteworthy.

Year to date, the stock has fallen by nearly 45%, which is by no means normal for the healthcare stock. In fact, this is the worst it has performed since the Great Recession, when it tumbled by more than 54% in 2008.

UnitedHealth Group has attracted major contrarian investors like Buffett, Burry, and Simons. Click here to read why UNH stock is a Buy.

UnitedHealth Got a Boost From Berkshire’s Buying. 2 Reasons to Wait to Follow. UnitedHealth Group, the worst-performing stock in the Dow Jones Industrial Average so far this year, got a major boost last week from billionaire investor Warren Buffett. That doesn’t mean everyone else should buy.

NEW YORK] The Warren Buffett effect is proving true once again, spurring UnitedHealth Group’s reversal this month and giving the Dow Jones Industrial Average a push towards its first closing high since last year.